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Re: Fuel Gauge OR Sending Unit -- What's WRONG?

From: Hank Dozier
Date: March 16, 2002


Brandon...Seperately I am sending you the Service Manual pages for diagnosis (from 57 DeSoto, but should be the same). You need to fill your tank to known full, and then measure the resistance of the snesor/float assmbly. Also need to pump the tank and get that value as well. This gives you the high and low level resistances for the next step. Now remove the sensor/float as indicated in the manual and then with an Ohmmeter on the sensor, you can raise it to the "Full" value. hold it in place and hook it up to the gauge like in the book, and see what it reads. Do the same at the empty resistance. Set these resistances before connecting the the sensor/float, because the voltage sourced from the gauge assembly will throw off the resistance. If it reads correctly outside the vehicle, most likely the tank grounding needs cleaning. If not, then you need to clean the contacts on the instrument cluster connections. Also examine the float to make sure it has not absorbed fuel and water and is not "heavy", or possibly the lever arm has been bent so it reads incorrectly. Good luck.


Last changed: July 19, 2018